TW202207483A - Fluorescent plate, wavelength conversion member, and light source device - Google Patents

Abstract

This fluorescent plate comprises a fluorescent phase that fluoresces due to excitation light and a plurality of voids. In a cross section of the fluorescent plate that includes cross sections of the voids, the standard deviation of the equivalent circle diameter of voids having an equivalent circle diameter of 0.4-50 [mu]m inclusive is less than or equal to 1.5.

Description

Fluorescent plate, wavelength conversion member, and light source device

The present invention relates to a fluorescent plate, a wavelength conversion member and a light source device.

Conventionally, a fluorescent plate that emits fluorescent light when irradiated with light has been known. In recent years, there has been known a highly functional fluorescent plate having a fluorescent phase that emits light of a wavelength different from that of the irradiated light when the fluorescent phase is irradiated with light. For example, Patent Document 1 discloses a technique of forming a space inside a fluorescent plate for reflecting light by a fluorescent phase. [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent No. 5989268

[The problem to be solved by the invention]

However, in order to improve the light extraction efficiency in the fluorescent plate, there is still room for improvement in the aforementioned prior art. For example, the phosphor plate described in Patent Document 1 includes a plurality of voids with a wide distribution of inner diameters ranging from voids smaller than 3 μm to voids larger than 12 μm. In this way, if there is a variation in the inner diameter of the void, the variation in the scattering direction of the light scattered in the void also increases, which may reduce the light extraction efficiency in the phosphor plate.

An object of the present invention is to provide a technique that can improve the extraction efficiency of light in a fluorescent plate. [means to solve the problem]

The present invention has been accomplished in order to solve at least a part of the above-mentioned problems, and can be realized as the following aspects.

(1) According to an aspect of the present invention, a phosphor plate is provided. The fluorescent plate includes: a fluorescent phase that emits fluorescent light by excitation light; and a plurality of voids; and in the cross section of the fluorescent plate including the voids, an equivalent circle diameter is 0.4 μm or more and 50 μm or less. The standard deviation of the equivalent circle diameter of the void is 1.5 or less.

According to this configuration, the fluorescent plate has voids such that the standard deviation of the equivalent circle diameters of voids having an equivalent circle diameter of 0.4 μm or more and 50 μm or less in a cross section of the fluorescent plate including the voids is 1.5 or less. That is, in the fluorescent plate, the variation of the equivalent circle diameter of the voids having an equivalent circle diameter of 0.4 μm or more and 50 μm or less is relatively small, and the fluorescent plate has voids of similar size. Thereby, since the reflection deviation of the light in the voids on the fluorescent phase is small, the reflectivity of the voids can be improved compared with the case where there is a large deviation in the equivalent circle diameter of the voids. Therefore, the extraction efficiency of light can be improved in the fluorescent plate.

(2) In the fluorescent plate of the above-mentioned form, the ratio of the number of voids with an equivalent circle diameter of 1 μm or more and less than 10 μm among the voids with an equivalent circle diameter of 0.4 μm or more and 50 μm or less may be 90% or more. . According to this configuration, in the fluorescent plate, the ratio of the number of voids with an equivalent circle diameter of 1 μm or more and less than 10 μm among the voids with an equivalent circle diameter of 0.4 μm or more and 50 μm or less is 90% or more. Thereby, since the reflection deviation of the light on the fluorescent phase in the voids is further reduced, the reflectance of the voids can be further improved. Therefore, the extraction efficiency of light can be further improved in the fluorescent plate.

(3) In the fluorescent plate of the above-mentioned form, in the cross-section of the cross-section of the fluorescent plate including the voids, the ratio of the area occupied by the voids having an equivalent circular diameter of 0.4 μm or more and 50 μm or less may be 3%. Above and below 15%. According to this configuration, in the fluorescent plate, the ratio of the area of the space having an equivalent circle diameter of 0.4 μm or more and 50 μm or less in the cross section of the fluorescent plate is 3% or more and 15% or less. When the area ratio of the cross section of the phosphor plate is small, the reflectivity is lowered due to the small number of reflections. In addition, when the area ratio of the cross-section of the fluorescent plate is large, since the distance between adjacent voids is shortened, repeated reflections occur and the light is easily attenuated. In the fluorescent plate of the above-mentioned form, by suppressing the occurrence of these drawbacks, the extraction efficiency of light to the outside of the fluorescent plate can be improved.

(4) In the phosphor plate of the above-mentioned form, a light-transmitting phase for transmitting the excitation light is further provided, and in the cross-section of the cross-section of the phosphor plate including the void, the fluorescent phase is opposite to the fluorescent phase and the light-transmitting phase. The area ratio of the total amount of the fluorescent plate may be 95% or less. When a phosphor plate is manufactured, if the number of voids formed by sintering increases, the voids become distorted, and the standard deviation of the equivalent circle diameter tends to deteriorate. According to the above-mentioned configuration, since the area ratio of the phosphor to the total of the phosphor phase and the light-transmitting phase in the phosphor plate is 95% or less, sintering is facilitated, and it becomes difficult to form voids. As a result, it is difficult for the void to form a twisted shape, so that the deterioration of the standard deviation of the equivalent circle diameter can be suppressed. Therefore, a decrease in the extraction efficiency of light toward the outside of the fluorescent plate can be suppressed.

(5) According to another aspect of the present invention, a wavelength conversion member is provided. The wavelength conversion member includes: the fluorescent plate; and a reflection member disposed on the fluorescent plate and reflecting the excitation light and the fluorescent light. According to this configuration, the wavelength conversion member includes the reflection member for reflecting the fluorescent light and excitation light emitted from the fluorescent plate. Thereby, the light emitted in the direction different from the predetermined direction of the light to be irradiated on the fluorescent plate is reflected in the predetermined direction by the reflecting plate, so that the amount of light emitted from the wavelength conversion member can be increased.

(6) The wavelength conversion member of the aforementioned aspect may include a heat-dissipating member that radiates the heat of the phosphor plate to the outside. According to this configuration, the wavelength conversion member includes the heat dissipation member for radiating the heat of the phosphor plate to the outside. As a result, on the fluorescent plate, the heat generated when the fluorescence is emitted by the excitation light can be efficiently discharged to the outside, so that the extinction caused by the temperature rise of the fluorescent plate can be suppressed. Therefore, a decrease in the amount of light emitted from the wavelength conversion member can be suppressed.

(7) According to another aspect of the present invention, a light source device is provided. The light source device may include: the wavelength conversion member; and a light source for irradiating the excitation light to the fluorescent plate. According to this configuration, the light source device includes the light source for irradiating the fluorescent plate with excitation light. When the light source irradiates the fluorescent plate with excitation light, the fluorescent plate emits fluorescent light by the excitation light. The light including the emitted fluorescent light is reflected on the surface where the fluorescent phase exposed in the space is more abundant, so that the amount of light radiated to the outside of the fluorescent plate can be increased. Thereby, the luminous intensity of the light source device can be improved.

Furthermore, the present invention can be implemented in various forms, for example, a method for manufacturing a fluorescent plate, a method for manufacturing a wavelength conversion member, a method for manufacturing a light source device, a system including a light source device, a method for controlling a light source device, a method for manufacturing a manufacturing device. It is realized in the form of a computer program, etc. of the light source device.

[Form for carrying out the invention]

<First Embodiment> FIG. 1 is a schematic diagram of a light source device 3 including the phosphor plate 1 of the first embodiment. The fluorescent plate 1 of the present embodiment emits light having a wavelength different from that of the light L1 as fluorescent light when irradiated by the light L1. The light L1 is a light emitting diode (LED: Light Emitting Diode) included in the light source device 3 . or a light source 9 such as a semiconductor laser (LD: Laser Diode) to emit. The fluorescent light emitted from the fluorescent plate 1 is emitted in a predetermined direction as light L2 together with the light on the fluorescent plate 1 that does not contribute to the generation of the fluorescent light. As shown in FIG. 1 , the light source device 3 of the present embodiment is a reflection type light source device, and is used in various optical devices such as headlights, lighting, and projectors. The light source device 3 includes the aforementioned light source 9 and the wavelength conversion member 2 . The wavelength conversion member 2 includes a fluorescent plate 1 , a reflection member 6 , a heat dissipation member 7 , and a bonding layer 8 . Furthermore, for the convenience of description, the respective size relationships of the respective components in FIG. 1 are illustrated in a manner different from the actual relationship.

The phosphor plate 1 is a flat plate member formed of a ceramic sintered body. An incident surface 1 a on which the light L1 is incident and a back surface 1 b located on the opposite side of the incident surface 1 a are formed on the fluorescent plate 1 . The fluorescent plate 1 emits fluorescent light by using the light L1 incident from the incident surface 1a as excitation light. The fluorescent plate 1 generates heat when emitting fluorescent light. The detailed structure of the fluorescent plate 1 will be described later.

The reflection member 6 is a thin film mainly composed of silver (Ag), and is formed on the back surface 1 b of the phosphor plate 1 . The reflection member 6 reflects the light L1 emitted by the light source 9 that penetrates the fluorescent plate 1 and the fluorescent light emitted from the fluorescent plate 1 in the direction toward the rear surface 1b toward the incident surface 1a. Furthermore, the reflection member 6 may be formed of a material with high reflectivity such as silver alloy or aluminum (Al).

The heat-dissipating member 7 is a flat plate member formed of a material having higher thermal conductivity than the fluorescent plate 1 , such as copper, copper-molybdenum alloy, copper-tungsten alloy, aluminum, and aluminum nitride. The heat dissipation member 7 is used to dissipate the heat of the phosphor plate 1 through the bonding layer 8 to the outside. In addition, the heat dissipation member 7 may be a single-layer structure made of the aforementioned materials, or a multilayer structure made of the same or different materials. In addition, a metal film for improving the adhesion with the bonding layer 8 may be arranged on the surface 7a of the heat dissipation member 7 on the phosphor plate 1 side.

The bonding layer 8 is disposed between the reflection member 6 and the heat dissipation member 7 and is formed of gold (Au) and tin (Sn). The bonding layer 8 is used to bond the fluorescent plate 1 and the heat dissipation member 7 and transfer the heat generated in the fluorescent plate 1 to the heat dissipation member 7 . In addition, the bonding layer 8 may be formed by not only gold and tin, but also a solder formed of other materials, or may be formed by sintering fine powders such as silver or copper (Cu).

FIG. 2 is an enlarged cross-sectional view of the fluorescent plate 1 . Next, the features of the phosphor plate 1 of the present embodiment will be described. As shown in FIG. 2 , the fluorescent plate 1 has a fluorescent phase 10 , a transparent phase 20 and a void 30 .

The fluorescent phase 10 is composed of a plurality of fluorescent crystal particles. In the present embodiment, the fluorescent crystal particles have a composition (so-called garnet structure) represented by the chemical formula A ₃ B ₅ O ₁₂ : Ce. Here, "A ₃ B ₅ O ₁₂ : Ce" means that Ce is solid-dissolved in A ₃ B ₅ O ₁₂ and a part of element A is substituted with Ce. Chemical formula A ₃ B ₅ O ₁₂ : Element A and element B in Ce are each composed of at least one type of element selected from the following element groups. Element A: Lanthanide elements other than Sc, Y, Ce (wherein, element A may further include Gd) Element B: Al (however, element B may further include Ga) The composition of the optical crystal particles and the types of elements are not limited to the aforementioned compositions and types of elements, and one fluorescent phase 10 may be composed of a plurality of types of fluorescent crystal particles.

The light-transmitting phase 20 is composed of a plurality of light-transmitting crystal particles. The translucent crystal particles have a composition represented by the chemical formula Al ₂ O ₃ . The light-transmitting phase 20 is used to transmit light inside the fluorescent plate 1 , and also serves as a heat transfer path for efficiently transferring the heat generated when the fluorescent phase 10 emits fluorescent light to the heat-dissipating member 7 . The refractive index of the transparent phase 20 is smaller than that of the fluorescent phase 10 .

The void 30 is formed by being surrounded by the fluorescent phase 10 and the light-transmitting phase 20 . As shown in FIG. 2 , the fluorescent plate 1 has a plurality of voids 30 . In the present embodiment, in the cross section of the fluorescent plate 1 including the voids 30 , the standard deviation of the equivalent circle diameter of the voids 30 having an equivalent circle diameter of 0.4 μm or more and 50 μm or less is 1.5 or less. In addition, the ratio of the number of voids 30 having an equivalent circle diameter of 1 μm or more and less than 10 μm among the voids 30 having an equivalent circle diameter of 0.4 μm or more and 50 μm or less is 90% or more. This shows that the deviation of the equivalent circle diameters of the plurality of voids 30 of the fluorescent plate 1 is small. This is because, in the method for producing the phosphor plate 1 to be described later, the particle size of the pore-forming material used as the raw material is uniform, and the pore-forming material is sufficiently dispersed in the raw material. In this embodiment, the average equivalent circle diameter of the voids 30 is preferably between 1 μm and 10 μm. If the average equivalent circle diameter is within this range, the reflectivity of visible light in the voids can be improved. The refractive index of the voids 30 is smaller than the refractive index of the transparent phase 20 . That is, the refractive index of the voids 30 is smaller than the refractive index of the fluorescent phase 10 .

Furthermore, in the present embodiment, in the cross section of the fluorescent plate 1 including the voids 30 as shown in FIG. 3% or more and 15% or less. In other words, it can be said that in the fluorescent plate 1 , the voids 30 having an equivalent circle diameter of 0.4 μm or more and 50 μm or less exist in the fluorescent plate 1 by a volume ratio of 3% or more and 15% or less. In addition, in this embodiment, in the cross section of the fluorescent plate 1 including the voids 30 , the area ratio of the fluorescent phase 10 to the total of the fluorescent phase 10 and the transparent phase 20 occupied by the fluorescent plate 1 is 60%. In other words, the part of the fluorescent plate 1 other than the voids 30 is composed of the fluorescent phase 10 with a volume ratio of 60% and the light-transmitting phase 20 with a volume ratio of 40%. Preferably, the area ratio of the fluorescent phase 10 is 95% or less, so that sintering is easy and voids are difficult to form.

Next, the manufacturing method of the fluorescent plate 1 is demonstrated. In the manufacturing method of the fluorescent plate 1, first, the weighed Al ₂ O ₃ , Y ₂ O ₃ , and CeO ₂ were put into a ball mill together with pure water, and pulverized and mixed for 16 hours. The slurry thus obtained by pulverizing and mixing is dried, and granulated with a spray dryer using the dried slurry. Next, a predetermined amount of a pore-forming material and a predetermined amount of a binder are mixed with the granulated particles, and kneaded while applying high shear force using a screw-type kneader to produce kneaded clay. By kneading while applying a high shearing force, the pore-forming material is uniformly dispersed and becomes difficult to agglomerate, so that the standard deviation of the equivalent circle diameter caused by the aggregation of the pore-forming material can be reduced. The phosphor plate 1 is produced by forming the produced kneaded material into a sheet shape using an extrusion molding machine, and firing and sintering it in an atmospheric environment of 1700°C.

Moreover, when manufacturing the wavelength conversion member 2 provided with the fluorescent plate 1, silver is vapor-deposited or sputtered on the back surface 1b of the fluorescent plate 1, and the reflection member 6 is formed into a film. Next, heating is performed in a reflow furnace in a nitrogen atmosphere or a hydrogen atmosphere in a state where the gold-tin solder foil is sandwiched between the reflection member 6 and the heat dissipation member 7 formed on the phosphor plate 1 . Thereby, the fluorescent plate 1 and the heat dissipation member 7 are joined, and the wavelength conversion member 2 is manufactured. Furthermore, gold-tin solder paste may be applied to join the phosphor plate 1 and the heat dissipation member 7 instead of using gold-tin solder foil.

Furthermore, in the case of manufacturing the light source device 3 including the wavelength conversion member 2, the light source 9 is set so that light is irradiated on the incident surface 1a of the fluorescent plate 1 included in the wavelength conversion member 2, and the wavelength conversion member 2 and the light source 9 are package. Thereby, the light source device 3 is manufactured.

Next, the contents and results of the evaluation test of the fluorescent plate 1 of the present embodiment will be described. In this evaluation test, the light extraction efficiency of the sample was evaluated by producing a plurality of samples of the fluorescent plate and measuring the brightness of the sample when light was irradiated on each sample. In this evaluation test, three items were focused on (i) the standard deviation of the equivalent circle diameter of the voids, (ii) the equivalent circle diameter of the voids, and (iii) the area ratio of the voids on the cross section of the fluorescent plate. evaluation test.

In this evaluation test, the characteristics of the samples were measured using the following methods. ‧Equivalent circle diameter of void The samples were cut, and the mirror-finished cut surfaces were observed by FE-SEM. In the image analysis using WinROOF, cross-sectional images were acquired at arbitrary 5 points, and the equivalent circle diameter of the void was measured by the interception method. ‧Dispersibility The distribution (vertical axis: frequency, horizontal axis: equivalent circle diameter) of the measured voids was calculated using the aforementioned interception method. At this time, the difference in the equivalent circle diameter at which the frequency is 5% of the whole is calculated from the equivalent circle diameter showing the maximum frequency, and used as dispersion. ‧standard deviation The standard deviation is calculated from the equivalent circle diameter of the voids measured using the interception method described above. ‧Area ratio of voids In the cross-sectional image of the sample binarized by image processing, the total area of the plurality of voids and the area of the portion other than the voids are calculated, and the ratio of the total area of the plurality of voids to the area of the entire cross-sectional image is calculated. . ‧brightness The sample was polished so that the thickness of the sample became 200 μm, and the surface was mirror-finished to prepare a sample for luminance measurement. The sample for luminance measurement was irradiated with a laser having a wavelength of 450 nm (laser diameter: 0.4 mm, laser power: 5 W), and the light in the reflection direction was measured using a luminance meter.

FIG. 3 is a diagram showing the first result of the evaluation test of the phosphor plate 1 of the first embodiment. FIG. 4 is a diagram showing the second result of the evaluation test of the phosphor plate 1 of the first embodiment. FIG. 5 is a diagram showing the third result of the evaluation test of the phosphor plate 1 of the first embodiment. Next, the results of the evaluation test for each of the aforementioned three items will be described.

(i) Standard deviation of the equivalent circle diameter of the voids The samples used for the evaluation test are in the method following the above-mentioned manufacturing method of the fluorescent plate 1, by taking the ratio of the fluorescent phase in one sample as the volume ratio of 60%. Al ₂ O ₃ , Y ₂ O ₃ , and CeO ₂ were weighed in a manner to change the particle size distribution of the pore-forming material mixed in the granulated particles, to prepare the kneaded clays of sample 1, sample 2 and sample 4. In addition, sample 3 is made of clay without adding pore-forming material. Figure 3 shows the test results regarding the standard deviation of the equivalent circle diameter of the voids. The sample 1 shown in the table of FIG. 3 is a sample which simulates the fluorescent plate 1 of this embodiment, and is used as a reference sample in this evaluation test. As shown in FIG. 3 , when the standard deviation was 1.5 or less, it was confirmed that the luminance was 500 cd/mm ² or more. On the other hand, in the sample 3 with no voids and the sample 4 with a standard deviation of 7.4, the luminance was confirmed to be 350 cd/mm ² or less.

(ii) The samples for the evaluation test of the equivalent circle diameter of the voids were prepared by changing the particle size distribution of the pore-forming material in the method following the manufacturing method of the fluorescent plate 1 described above. Figure 4 shows the test results with respect to the equivalent circle diameter of the voids. Sample 1 shown in the table of FIG. 4 is the benchmark sample also shown in FIG. 3 . As shown in FIG. 4 , when the equivalent circle diameter of the void was 1.0 μm and 10 μm, it was confirmed that the luminance was lower (1.0 μm: 450 cd/mm ² , 10.0 μm: 360 cd/mm ² ). On the other hand, when the equivalent circle diameter of the void was larger than 1.0 μm and smaller than 10 μm (3.5 μm, 4.2 μm, 5, and 4 μm), it was confirmed that the luminance reached 600 cd/mm ² or more, which was a high value.

(iii) The samples for the evaluation test of the area ratio of the voids on the cross section of the fluorescent plate were prepared by changing the amount of the pore-forming material in the method following the manufacturing method of the fluorescent plate 1 described above to prepare samples 9 to 12. FIG. 5 shows the experimental results regarding the area ratio of the voids on the cross section of the phosphor plate. Sample 1 shown in the table of FIG. 5 is the reference sample also shown in FIG. 3 . As shown in FIG. 5 , when the area ratio of the voids was 1% and 30%, it was confirmed that the luminance was lower (1%: 330 cd/mm ² , 30%: 280 cd/mm ² ). On the other hand, when the area ratio of voids was 3% or more and 15% or less (3%, 8%, 15%), it was confirmed that the luminance was 670 cd/mm ² or more, which was a high value.

According to the fluorescent plate 1 of the present embodiment described above, the gap 30 provided in the fluorescent plate 1 is one of the gaps 30 having an equivalent circle diameter of 0.4 μm or more and 50 μm or less in a cross section of the fluorescent plate 1 including the gap 30 . The standard deviation of the equivalent circle diameter is 1.5 or less. That is, in the fluorescent plate 1 , the deviation of the equivalent circle diameter of the voids 30 having an equivalent circle diameter of 0.4 μm or more and 50 μm or less is relatively small, and the fluorescent plate 1 has voids 30 of similar size. As a result, since the reflection deviation of the light on the fluorescent phase 10 in the voids 30 is small, the reflectivity of the voids 30 can be improved compared with the case where there is a large variation in the equivalent circle diameter of the voids 30 . Therefore, the extraction efficiency of light can be improved in the fluorescent plate 1 .

In addition, according to the fluorescent plate 1 of the present embodiment, in the fluorescent plate 1, among the voids 30 having an equivalent circle diameter of 0.4 μm or more and 50 μm or less, the number of voids 30 having an equivalent circle diameter of 1 μm or more and less than 10 μm in the number of the voids 30 . ratio of more than 90%. Thereby, since the reflection deviation of the light on the fluorescent phase 10 in the voids 30 is further reduced, the reflectance of the voids 30 can be further improved. Therefore, the light extraction efficiency can be further improved in the fluorescent plate 1 .

In addition, according to the fluorescent plate 1 of the present embodiment, in the fluorescent plate 1, the ratio of the area of the space 30 having an equivalent circle diameter of 0.4 μm or more and 50 μm or less in the cross section of the fluorescent plate 1 is 3% or more and 15%. the following. When the area ratio of the cross section of the phosphor plate is small, the reflectivity is lowered due to the small number of reflections. In addition, when the area ratio of the cross-section of the fluorescent plate is large, since the distance between adjacent voids is shortened, repeated reflections occur and the light is easily attenuated. In the fluorescent plate 1 of the present embodiment, by suppressing the occurrence of these disadvantages, the extraction efficiency of light to the outside of the fluorescent plate 1 can be improved.

In addition, when the number of voids formed by sintering increases when the phosphor plate is manufactured, the voids become distorted, and thus the standard deviation of the equivalent circle diameter tends to deteriorate. According to the fluorescent plate 1 of the present embodiment, in the cross-section of the fluorescent plate 1 including the voids 30 , the area ratio of the fluorescent phase 10 to the fluorescent phase 10 and the light-transmitting phase 20 in the total of the fluorescent plate 1 is 60% . As a result, in the phosphor plate 1 of the present embodiment, since sintering is easy, it becomes difficult to form voids, so that it is difficult for the voids to form a distorted shape, and the deterioration of the standard deviation of the equivalent circle diameter can be suppressed. Therefore, a decrease in the extraction efficiency of light toward the outside of the fluorescent plate 1 can be suppressed.

Further, according to the wavelength conversion member 2 of the present embodiment, the wavelength conversion member 2 includes the reflection member 6 that reflects the fluorescent light and excitation light emitted from the fluorescent plate 1 . Thereby, for example, as shown in FIG. 1 , the light emitted in the direction different from the direction of the light L2 to be irradiated on the fluorescent plate 1 is reflected in a predetermined direction by the reflection member 6, so that the number of self-wavelength conversion members 2 can be increased. The amount of light emitted.

In addition, according to the wavelength conversion member 2 of the present embodiment, the wavelength conversion member 2 further includes the heat dissipation member 7 for emitting the heat of the fluorescent plate 1 to the outside. As a result, the fluorescent plate 1 can efficiently dissipate heat generated when the fluorescent plate 1 emits fluorescence by the excitation light to the outside, so that the extinction caused by the temperature rise of the fluorescent plate 1 can be suppressed. Therefore, a decrease in the amount of light emitted from the wavelength conversion member 2 can be suppressed.

Further, according to the light source device 3 of the present embodiment, the light source device 3 includes the light source 9 for irradiating the light L1 on the fluorescent plate 1 . When the light source 9 irradiates the fluorescent plate 1 with the light L1, the fluorescent plate 1 emits fluorescent light by a part of the light L1. The fluorescent light emitted from the fluorescent plate 1 is reflected on the surface of the fluorescent phase 10 exposed to the voids 30 in large quantities, so that the amount of light emitted to the outside of the fluorescent plate 1 can be increased. Thereby, the light emission intensity of the light source device 3 can be improved.

<Variation of this embodiment> The present invention is not limited to the above-described embodiments, and can be implemented in various forms within the scope of the essential content, and for example, the following modifications can be made.

[Variation 1] In the aforementioned embodiment, the equivalent circle diameter of 90% or more of the voids 30 having an equivalent circle diameter of 0.4 μm or more and 50 μm or less is assumed to be 1 μm or more and less than 10 μm. However, the ratio of the voids 30 having an equivalent circle diameter of 1 μm or more and less than 10 μm is not limited to this. It may be less than 90%, as long as the standard deviation of the equivalent circle diameter of voids having an equivalent circle diameter of 0.4 μm or more and 50 μm or less is 1.5 or less.

[Variation 2] In the aforementioned embodiment, in the cross section of the fluorescent plate 1 including the voids 30, the ratio of the area occupied by the voids 30 having an equivalent circular diameter of 0.4 μm or more and 50 μm or less is assumed to be 3% or more and 15%. the following. However, the ratio of the area occupied by the voids 30 having an equivalent circle diameter of 0.4 μm or more and 50 μm or less is not limited to this. It can be less than 3% or more than 15%, but if the gap is too small, the reflection effect in the gap will be small. If the gap is too large, the light will be attenuated due to the increase in the number of reflections and the reflectivity will decrease. Therefore, it is preferably more than 3%. and below 15%.

[Variation 3] In the foregoing embodiment, in the cross section of the fluorescent plate 1 including the voids 30 , the area ratio of the fluorescent phase 10 to the total of the fluorescent phase 10 and the transparent phase 20 occupied by the fluorescent plate 1 is assumed to be 60%. When the area ratio of the fluorescent phase 10 is less than 10% or more than 95%, since the sinterability of the sintered body itself cannot be improved, voids are likely to be generated in addition to the voids caused by the intentionally added pore-forming material. If such unintentional voids increase, voids in a distorted shape are likely to be formed, thereby possibly deteriorating the standard deviation of the equivalent circle diameter of the voids. Therefore, it is preferable that the area ratio of the phosphor phase 10 is 10% or more and 95% or less so that unintended voids are not formed as much as possible during the sintering of the phosphor plate 1 .

[Variation 4] In the aforementioned embodiment, the light source device 3 is assumed to be a reflection type light source device. However, the fluorescent plate 1 can also be applied to a transmission type light source device.

In the above, although this aspect has been described based on the embodiment and the modified example, the embodiment of the aforementioned aspect is intended to facilitate understanding of this aspect and is not intended to limit this aspect. This aspect can be changed and improved without exceeding the substantive content and the scope of the patent application, and its equivalents are also covered by this aspect. In addition, in this specification, as long as the technical features are not necessarily described, they can be deleted as appropriate.

1: fluorescent plate 2: wavelength conversion member 3: Light source device 6: Reflective member 7: heat dissipation components 8: Bonding layer 9: Light source 10: Fluorescent phase 20: Translucent phase 30: void

FIG. 1 is a schematic diagram of a light source device including the phosphor plate of the first embodiment. FIG. 2 is an enlarged cross-sectional view of the phosphor plate. FIG. 3 is a diagram showing the first result of the evaluation test of the phosphor plate of the first embodiment. FIG. 4 is a diagram showing the second result of the evaluation test of the phosphor plate of the first embodiment. FIG. 5 is a diagram showing the third result of the evaluation test of the phosphor plate of the first embodiment.

Claims (7)

A fluorescent plate is characterized by comprising: a fluorescent phase that emits fluorescent light by excitation light; and a plurality of voids; in the cross section of the fluorescent plate including the voids, the equivalent circle diameter is 0.4 μm or more and The standard deviation of the equivalent circle diameter of voids of 50 μm or less is 1.5 or less. The fluorescent plate of claim 1, wherein the ratio of the number of voids with an equivalent circle diameter of 1 μm or more and less than 10 μm among the voids with an equivalent circle diameter of 0.4 μm or more and 50 μm or less is 90% or more. The fluorescent plate according to claim 1 or 2, wherein in the cross section of the fluorescent plate including the voids, the ratio of the area occupied by the voids having an equivalent circle diameter of 0.4 μm or more and 50 μm or less is 3% or more and 15% %the following. The phosphor plate according to any one of claims 1 to 3, further comprising a light-transmitting phase for transmitting the excitation light, and in the cross-section of the cross-section of the phosphor plate including the voids, the phosphor is opposite to the phosphor phase and The area ratio of the light-transmitting phase to the total sum of the fluorescent plate is less than 95%. A wavelength conversion member characterized by comprising: the fluorescent plate according to any one of claims 1 to 4; and a reflection member disposed on the fluorescent plate and reflecting the excitation light and the fluorescent light. The wavelength conversion member of claim 5, further comprising a heat-dissipating member that discharges the heat of the phosphor plate to the outside. A light source device comprising: the wavelength conversion member according to claim 5 or 6; and a light source that emits light to the phosphor plate.

Images